Method of testing milk.



UNITED STATES PATENT OFFICE.-

OSGAR WENDLER, OF LEIPSIC, GERMANY, ASSIGNOR TO DR. N. GERBERS CO.GESELLSCHAFT MIT 'BESOHRAENKTER HAFTUNG, OF LEIPSIC,

GERMAN 1 Specification of Letters Patent.

T-atented July 31, 1906.

Application filed February 28, 1906. Serial No. 303.566.

To all whom it may concern.-

Be it known that I, OSCAR WENDLER, a subject of the King of Prussia,German Emperor, and a resident of Leipsic, Germany, have invented acertain new and useful Improvement in Methods of Testing Milk, of whichthe following is a specification.

[fiThe methods for rapid determination of the fat in milk and the likeare based on this that the fat-incasing materials in solution and thefat are separated entirely by means of centrifugal force. The onlycentrifugal method heretofore found to be practical is that of Gerber.According to Gerbers method the substance to be experimented with iswell mixed with concentrated sulfuric acid, with an addition of amylalcohol, and after being centrifugalized the layer of fat is read off atabout 70 centigrade. Although for Gerber s method the employment of sucha high temperature, which may even be increased by mixing the substanceunder analysis with concentrated sulfuric acid, has not proved to beprejudicial for experimental results, yet the handling of a butyrometerat such a high temperature is inconvenient for many. It may also happenthat the rubber stopper closing the butyrometer may spring out inconsequence of the high temperature and the operator might be injured bythe sulfuric acid bursting out.

Under the present invention the employment of concentrated sulfuric-acidand also of a high temperature is avoided. Instead of sulfuric acidbeing employed as a solvent for the albuminous materials incasing thefat there is employed an alkaline solution to which tartaric salts areadded. The maximum temperature allowed with the improved method is fromabout 45 to centigrade, at which no trouble is experienced in handlingthe butyrometer.

It is not broadly new to employ alkalies for the determination of thefat in milk. One of the oldest methodsthat of Marchand, as also that ofSoxhletis based thereon. Neither of these methods was, however, a methodof rapidly determining the proportion of fat. Recently another methodhas been proposedthe ,so-called sinacid methodwhich also avoids the useof acid and is based on the employment of trisodium phosphate. Apartfromthe consideration that the practicability of the sinacid method isdoubtful (see the article by Dr. M. 5 5

mary object of the present invention to avoid such high temperatures.With such temperatures, as in the case of the sinacid method, there is adanger of saponification of the fat, which is avoided in Gerbers method,

owing to the acid nature of the reagents.

According to the present invention, which avoids the use of acid, theproportions are so chosen that a perfect separation of the fat iseffected, but without saponification. A

further important advantage of the present invention is that thebutyrometers presently in use can be employed without change, requiringthe same quantities of milk and of liquid reagent, the measuringinstruments in use being suited therefor.

As in the case of Gerbers acid method, there is also added under myinvention a small quantity of a high-boiling alcohol, such as amylalcohol or isobutyl alcohol, butyl alcohol, or propyl alcohol, eitherpure or diluted with low-boiling alcohols.

It has been determined that a proportion of only six per cent. hydratesufiices for the liquid reagent serving for the separation of the fat.most desirable Rochelle salti. e., potassiosodio-tartrate.

Experiments have shown that the duration of the reaction may beshortened if so- As the tartaric salt I have found dium chlorid be addedto the liquid reagent, 0

the further advantage resulting that corresponding to the addition ofsodium chlorid the proportion of alcohol may be diminished, wherebygreater exactitude in the results is obtained.

As an example I introduce into the butyrometer in the following order:eleven cubic centimeters liquid reagent, (about ten per cent. N aOH,about five per cent. Rochelle salt, about ten per cent. NaCl,) ten cubiccen-' 10o timeters milk, 0.6 cubic centimeters isobutyl alcohol, or asuitable quantity of the abovenamed alcohols, and close the instrumentwith a dry rubber stopper, which is driven in so far that the liquidstands in the upper half 10 5 of'the scale. The contents of thebutyrometer are shaken up and thoroughly mixed by turning the instrumentupside down three times, in which in order to effect perfect mixturecare has to be taken that each time the instrument is turned upside downthe liquid should always flow entirely down. The

butyrometer is then brought for two or three minutes into a water-bathat about 45, then removed, again well shaken and mixed by turning theinstrument upside down two or three times, and centrifu alized for aboutthree minutes at the rate 0 eight hundred to twelve hundred revolutionser minute. The butyrometer is then placed or some minutes in thewater-bath and the reading then taken at about 45. 1

Having now described my invention, what I claim, and desire to secure byLetters Patent of the United States, is-

1. The improved method of determining rapidly the proportionof fat inmilk and the like consisting in reacting on the milk with alkalitogether with tartaric salts at a term perature of about 45, andseparating the fat from the solution by centrifugal action.

2. The improved method of determining rapidly the proportion of fat inmilk and the like consisting in reacting on the milk with alkalitogether with tartaric salts and sodium chlorid, and se arating the fatfrom the solution by centri gal action.

In testimony whereofI have signed' my 0 name to this specification inthe presence of two subscribing witnesses.

OSCAR WENDLER.

Witnesses: o

R. FAUDEI, R. WITZSCHEL.

